Effect of Lipid Source and Concentration on Somatic Growth of Juvenile Green Sea Urchins, Strongylocentrotus droebachiensis

Supplying juvenile sea urchins with an abundant supply of resources and essential nutrients for growth will facilitate somatic growth and, hence, improve the success of the sea urchin aquaculture industry. Lipids are essential in physical processes such as membrane production and are a concentrated source of energy. This study, using prepared diets, tested the effects of lipid sources containing different major fatty acids (i.e., n‐3 and/or n‐6) (Part 1) and lipid concentration (i.e., 1, 3, 7, and 10%) (Part 2) on the somatic (i.e., test or shell) growth of two size cohorts (7.0‐ and 15.3‐mm average initial test diameter [TD]) of juvenile green sea urchins, Strongylocentrotus droebachiensis. The growth of the sea urchins fed prepared diets was compared to the growth of sea urchins fed a kelp reference diet, Laminaria longicruris. After both feeding trials, the kelp‐fed sea urchins had superior test growth and were more similar in physical appearance to wild sea urchins (i.e., test color, spine length, and gonad color). The sea urchins fed the prepared diets had pale test color, short, stubby spines, and large, pale‐colored gonads compared to wild sea urchins. The smaller cohort of sea urchins grew at a faster rate, but growth patterns for both cohorts were similar. The juveniles fed the prepared diets (in both feeding trials) had high initial growth rates that decreased after approximately 100 d compared to the kelp‐fed juveniles. Differences in test growth were not shown to be affected by sea urchin size (i.e., similar results for both cohorts) or by differences in dietary lipid sources (i.e., the presence of n‐3 and/or n‐6 fatty acids). However, the sea urchins fed diets with lower lipid concentration (≤3%) had larger average TDs than those fed diets with higher lipid concentrations (≥7%). Differences in test growth and physical appearance among those fed the prepared diets and kelp may have been because of nutritional deficiencies in the prepared diets.     

Effect of Dietary Minerals and Pigment on Somatic Growth of Juvenile Green Sea Urchins, Strongylocentrotus droebachiensis

This study investigated the effects of dietary minerals and pigments in prepared diets on the somatic growth performance of wild and hatchery‐reared juvenile green sea urchins, Strongylocentrotus droebachiensis, by two feeding trials. In the first feeding trial, a modified Bernhart‐Tomerelli salt mix (BT) at 0, 1.5, 3, 6, and 15% dry mass and a Shur‐Gain/Maple Leaf Foods mineral mix at 3 and 6% dry mass were used to test for mineral effects. Pigment effects were tested by incorporating 1.25% Algro? to the prepared diets (i.e., 250 mg of beta‐carotene per kilogram of diet). Sea urchins (13–15 mm of initial test diameter [TD]) collected from the wild were fed the prepared diets over 154 d. The sea urchins that were fed the pigmented diets had significantly greater test growth than those fed the nonpigmented diets, and mineral concentration in the pigmented diets was directly related to juvenile size at the end of the feeding trial. A sample of juveniles from each treatment group was sacrificed to determine test, gonad, and gut yields and ash concentrations. Ash concentrations in the test and gonad were higher for juveniles fed pigmented diets than for those fed nonpigmented diets with similar mineral concentration, suggesting an interaction between minerals and pigments within the juvenile sea urchins. The second feeding trail used two size cohorts of hatchery‐reared juveniles ranging from 1–2 mm and 2–3 mm of initial TD to compare the growth of sea urchins fed either the pigmented diet with 15% BT (i.e., the best diet in the first feeding trial) or kelp, Laminaria longicruris, over 159 d. Growth performance was similar for both cohorts, indicating no size effect, but the juveniles fed the prepared diet were significantly larger at the end of the feeding trial than those fed kelp. This suggests that prepared diets with pigment and high mineral concentration can outperform kelp, and be utilized for juvenile green sea urchins to increase test growth.     

Growth of Juvenile Green Sea Urchins,Strongylocentrotus droebachiensis,Fed Formulated Feeds with Varying Protein Levels Compared with a Macroalgal Diet and a Commercial Abalone Feed

The effects of varying protein and carbohydrate levels in prepared diets on the somatic growth of juvenile green sea urchins, Strongylocentrotus droebachiensis, were examined. Ten diets were tested on 600 hatchery reared urchins (mean start weight = 0.11 g) for 6 mo with three replicate groups per diet. Nine of the diets were prepared specifically for urchins and varied in protein (16–40% protein) and carbohydrate (29–49% carbohydrate) levels. The other two diets consisted of a commercially available abalone diet and the kelp, Saccharina latissima. Weight measurements were carried out at 6‐wk intervals, and at the end of the study urchins were individually weighed and a subsample from each treatment was analyzed for gonad weight and color. End weights after 6 mo ranged from 2.56 g for urchins fed the abalone diet to 6.11 g for urchins fed one of the prepared diets. Most of the prepared feeds outperformed kelp, and significant differences in growth were detected between some of the diets. In general, diets with lower protein levels (16–22% protein) and higher carbohydrate levels (>40% carbohydrate) produced the fastest growth. However, further diet refinement and/or use of finishing diets may be necessary to optimize gonad quality.     

Effects of Hyperoxic Conditions on Growth Performance in Juvenile and Adult Green Sea Urchin,Strongylocentrotus droebachiensis

The effects of hyperoxic conditions on survival, gonad growth, feed intake, and food conversion of adult and somatic growth and survival of juvenile green sea urchin, Strongylocentrotus droebachiensis, were examined. Juvenile and adult sea urchins with initial diameters of 11.5 and 75 mm, respectively, were reared in water with constant oxygen saturations of 100 (control), 115 and 130% for 42 d (juvenile) and 51 d (adult sea urchin) at 8 C and 33‰ salinity. During the experiment the gonad indices of the adults tripled from 7.3% (±1.5) to 21.4% (±4.3), 19.4% (±4.7), and 22.0% (±4.4) for the groups kept at 100, 115, and 130% oxygen saturation, respectively. At the end of the experiment, the differences in gonadal size among the groups were not significant. Neither were there any significant differences in food intake or food conversion ratio among the groups. Only one animal died during the experiment. The juvenile sea urchin kept at 100, 115, and 130% oxygen saturation doubled their test diameter from initially 11.5 mm (±1.5) to 19.9 mm (±1.4), 21.4 mm (±2.1) and 20.6 mm (1.0), respectively, but there were no significant differences in growth among these groups. There was no mortality during the experiments in these groups. Overall, the findings suggest that juvenile and adult S. droebachiensis are unable to utilize hypersaturation of oxygen to increase somatic or gonad growth, but can be reared at hyperoxygenated water for prolonged periods of time without harmful effects.     

Long‐term Growth Study of Male and Female Green Sea Urchins,Strongylocentrotus droebachiensis,under Constant Light and Temperature Regime

Juvenile green sea urchins, Strongylocentrotus droebachiensis, with an initial mean test diameter of 9.5 mm (±1.2 SD) were held in the laboratory, in individual compartments and at constant temperatures (8.5 C) (n = 90) for a period of 99 wk. The animals were supplied with flow‐through sea water, and fed the Nofima sea urchin manufactured feed ad libitum. Growth, survival, feed intake, feed conversion ratio (FCR), and gonad index (GI) of the sea urchins were monitored during this period. The mortality was 11% throughout the experimental period. The test diameter (TD) increased significantly with time, best described by a polynomial equation (TD = 0.8756 + 0.584Time − 0.002Time², R² = 0.995). Sex was included as dummy variable, but did not contribute significantly; hence, there were no differences in growth trajectories between males and females. The study showed there were no significant differences in body wet weight or FCR between males and females. However at the end of the experiment the female urchins had a significantly higher GI of 31.1% (±4.4), compared with the male urchins which had an average GI of 26.8% (±5.4). In conclusion, the present study showed that male and female green sea urchins have the same growth capacity and feed convention ratio but by the end of the experiment the gonad index was significantly higher in female than male urchins.     

The Effect of Astaxanthin in Feed and Environmental Temperature on Carotenoid Concentration in the Gonads of the Green Sea Urchin Strongylocentrotus droebachiensis Müller

The aim of this study was to investigate the long term development of carotenoid concentration in gonads and gonad development of green sea urchins reared at different temperatures and fed formulated feed containing dwerent levels of astaxanthin. Urchins, sampled from a natural population, were reared under two different temperature regimes (7 C and 12 C) and fed formulated feed containing 0, 100 and 500 mg astaxanthin/kg feed, respectively. The study lasted 112 d. Astaxanthin was detected in the groups fed feed containing astaxanthm, but in low quantities. No effect of temperature was observed on the retention of astaxanthin. Echinenone values declined throughout the study, probably due to the lack of suitable metabolic precursor for production of echinenone. Water and lipid concentration in the gonads increased throughout the study indicating the progressions of gametogenesis and the generally improved nutritional status of the animals. No significant difference in gonad index (GI) due to treatment was observed but GI varied between the sexes with male GI increasing significantly faster compared to females.     

Optimizing Prepared Feed Ration for Gonad Production of the Green Sea Urchin Strongylocentrotus droebachiensis

Adult green sea urchins Strongylocentrotus droebachiensis were fed three different quantities (0.25, 0.50, 1.00% body weight/d) of a prepared feed during a 12‐wk experiment to determine the effect of food ration on gonad quantity and quality. A diet of kelp, Laminaria longicruris and/or L. digitata, fed at satiation (3% body weight/d) and urchins taken from the wild at the beginning and end of the experiment served as controls. Urchins fed prepared feed or kelp increased their percent gonad yield significantly over the experimental period. Affer 12 wk, individuals fed the prepared diet at 0.50 or 1.00% body weighffd had significantly higher percent gonad yields (mean ± SEM: 23.5 ± 0.6% and 23.4 ± 0.7%, respectively) than urchins fed at 0.25% body weight/d (18.0 ± 1.0%) or control animals given kelp (18.3 ± 0.8%). There was no significant difference in gonad yield between the 0.50 and 1.00% feeding levels. All feeding treatments had significantly higher percent gonad yields than urchins sampled from the wild at the end of the experiment that had recently spawned (2.8 ± 0.5%). There was no significant difference in gonad taste among urchins fed the prepared diet at 0.25% body weight/d, those given kelp, or those collected from the wild at the end of the experiment (good to very good ratings), but all of these treatments had significantly better tasting gonads than urchins given the prepared feed at 0.50 or 1.00% body weight/d (satisfactory ratings). Gonad taste rating of urchins fed a prepared diet was dependent on ration with greater feed amounts leading to worse tasting gonads (linear regression: r²= 0.68, P < 0.01). Gonad color, texture, and firmness did not differ significantly among any of the feed ration treatments or kelp control. Results suggest that the best ration for prepared feed would be 0.50% body weightld since this would optimize gonad yield while minimizing feed costs. Further research on prepared feeds is required to optimize both gonad color and taste.     

中间球海胆与光棘球海胆杂交子一代的生长比较研究

通过海胆杂交子一代与两亲本的中间育成、海上筏式养殖的生长对比,表明海胆杂交子一代具有杂交优势,养殖成活率比其母本高10%,且生长快、生殖腺指数高、颜色鲜艳。大连长海县獐子岛杂交海胆达5cm时间比大连凌水养殖的母本中间球海胆提前7个月。     

饵料对中间球海胆品质的影响

饵料种类对中间球海胆的品质有显著影响。长期摄食鲜海带或裙带菜的海胆生殖腺呈橘红色和橘黄色,摄食孔石莼为浅橘红色和橘黄色,摄食人工配合饲料为土黄色和乳白色。长期摄食鲜海藻类的海胆生殖腺味道甜美,口感上佳;而摄食人工配合饲料的则有苦涩味。饵料种类及其交替方式决定了海胆生殖腺色泽和口感的转变速度,其中鲜海藻类间转换速度基本一致,均需60d可完成;而人工配合饲料则需80d方能完成。中间球海胆消化道的颜色更易受饵料种类的影响,其转换速度与饵料种类和交替方式无关,20d即有明显表现,40d可完成。     

中间球海胆与光棘球海胆规模化杂交育苗技术

海胆规模化杂交育苗,受精率为33%,适宜的水温、光照及饵料等培养条件下,杂交海胆能够正常生长和附着变态,变态时间与母本相近。用0.1mol/L的KCl诱导5 min,杂交海胆全部变态。杂交海胆壳径>2~3 mm剥离进入网箱培育,有利于快速生长。稚胆培养温度以12~15℃为宜。     

光棘球海胆与虾夷马粪海胆摄食与吸收的初步研究

在同等摄食条件下,虾民粪海胆的生长明显快于光棘球海胆;虾夷马粪海胆的平均日摄食率,粗同化率高于光棘球海胆;     

中间球海胆与光棘球海胆杂交及子一代人工育苗技术

研究结果表明，虽然中间球海胆与光棘球海胆的繁殖时间有差异。但通过筛选能够同时得到自然成熟的精卵，在比正常海胆自交精子量高20-40倍的精子作用下，中间球海胆为母本，光棘球海胆为父本，杂交受精率为47.1%，而反交的受精率为1.9%，正反交受精率均低于自交组。在适宜的水温，光照及饵料等培养条件下，两杂交组均能够生长，附着变态，并且变态时间与母本相近。     

Formulated Feed Supports Weight Gain and Survivorship in Juvenile Sea Urchins Lytechinus variegatus

In adult sea urchins, formulated feeds can support both weight gain and gonad production; however, studies demonstrating the effects of formulated feeds on juvenile sea urchin growth are limited. In this study, juvenile sea urchins (test diameter: 3.20–7.33 mm, N = 12 per treatment) were reared individually in artificial seawater and fed with one of four experimental feeds: (1) mixed‐taxa algal biofilm (MTAB), (2) freeze‐dried MTAB, (3) a commercial, small‐mammal feed (Friskies^® cat treats), or (4) a semipurified feed formulated for sea urchins. The MTAB and sea urchin feed supported weight gain and survival throughout the study; however, those individuals fed with the sea urchin feed exhibited a short lag period at the onset of feeding. This short lag period may be, in part, because of an initial lack of attraction of the urchins to the formulated feed. Furthermore, we hypothesize that gut physiology or gut flora must acclimatize to a new diet (all sea urchins were reared initially on the MTAB diet). The freeze‐dried MTAB and mammal feed did not support substantial weight gain. This study suggests that sea urchin juveniles as small as 3–4 mm can utilize formulated feeds for growth.     

饵料对稚幼参生长变色的影响

报告了藻粉,浮泥,人工配合饵料,混合饵料对稚幼长岛县牝一海水育苗场变色的影响。经３个胸月的投喂试验。结果：人工配合饵料组稚幼参体长,体重增长较快,纯藻粉组,浮泥组投喂效果都较差。藻粉中添加部分“海丰”牌饲料预混剂和３０％的浮泥,对稚参有明显的助长作用,日均增长,增重是纯藻粉组的２倍以上,且明显快于人工配合饵料组。     

Effect of temperature on somatic growth and survivorship of early post-settled green sea urchins, Strongylocentrotus droebachiensis (Müller)

A laboratory experiment was run for 171 days to assess growth and survivorship of recently settled juveniles of the green sea urchin, Strongylocentrotus droebachiensis (Müller), reared at five temperatures: 4.7±0.8, 9.0±1.1, 12.9±1.1, 16.0±1.5 and 19.7±1.3°C (mean±SD, n=7942). Individual sea urchins were housed separately in PVC pots with Nitex mesh bottoms (10 per tank and five replicate tanks per temperature treatment) and fed a combination of benthic diatoms and macroalgae (Porphyra sp.). The test diameter of each urchin was measured and survivorship recorded on a monthly basis. Mean (±SE) test diameter of all individuals at the beginning of the experiment was 2.41±0.03 mm (n=250). At the end of the experiment, mean test diameter (±SE) was significantly larger at 9.0°C (8.46±0.06 mm) and 12.9°C (8.20±0.25 mm) than at 4.7°C (7.27±0.05 mm), 16.0°C (6.72±0.17 mm) and 19.7°C (2.65±0.24 mm) and significantly larger at 4.7 and 16.0°C than at 19.7°C. When growth was expressed as a per cent increase in test diameter from the start of the experiment, however, there were no significant pair‐wise differences among 4.7, 9.0, 12.9 and 16.0°C treatments at the end of the experiment, but all these treatments were significantly greater than at 19.7°C. Mean per cent survivorship (±SE) at the end of the experiment for the various temperature treatments was 76.0±6.0%, 90.0±5.5%, 100.0±0.0%, 98.0±2.0% and 26.0±11.2% at 4.7, 9.0, 12.9, 16.0 and 19.7°C respectively. Per cent survivorship was significantly greater at 4.7, 9.0, 12.9 and 16.0°C than at 19.7°C and significantly greater at 12.9 and 16.0°C than at 4.7°C. Mean area increase of urchins per replicate tank at the end of the experiment – taking into account both test diameter growth and survivorship – was significantly larger at 9.0 and 12.9°C than at 4.7, 16.0 and 19.7°C, and significantly larger at 4.7 and 16.0°C than at 19.7°C. The results of this study suggest that young juveniles of S. droebachiensis should be reared at 9–13°C in order to optimize production for aquaculture.     

Effects of restricted feeding regimes on growth and feed conversion on juvenile green sea urchin,Strongylocentrotus droebachiensis

Groups of juvenile green sea urchin, Strongylocentrotus droebachiensis (average wet weight = 3.3 g), were fed five different dry feed rations (0.2%, 0.4%, 0.8%, 1.2% and 2.4% of their body weight per week) under constant light and temperature conditions for 160 days (Experiment I) in groups to examine growth effects, and for 40 days as individual treatments (Experiment II) to examine feeding efficiency. There was 100% survival of the sea urchins during both experiments. In Experiment I, the lowest ration group (0.2%) had significantly lower growth than the rest of the groups. There was no significant differences in growth between the sea urchin fed ration over 0.4% dry feed of the body wet weight per week. In Experiment II, the lowest feed ration groups (0.2%) had significant lowest growth but had the best feed conversion ratio (FCR), using 0.5 g of feed of dry feed per gram of sea urchin wet weight body growth. The FCR increased with increasing feed ration and the 2.4% group had the poorest FCR, using 1.3 g of feed per gram weight gain. Results from Experiments I and II illustrate that juvenile green sea urchin can grow at a restricted feed ration that is under maximum feed intake, without reduction in growth.     

Effect of Dietary Protein Concentration on Growth and Processing Yield of Channel Catfish Ictalurus punctatus1

Abstract.— This study was conducted to evaluate the effect of dietary protein concentration and an all‐plant diet on growth and processing yield of pond‐raised channel catfish Ictalurus punctatus. Four diets were formulated using plant and animal proteins to contain 24%n, 28%, 32%, or 36% crude protein with digestible energy to protein (DE/P) ratios of 11.7, 10.2, 9.0, and 8.1 kcal/g, respectively. An all‐plant diet containing 28% protein with a DE/P ratio of 10.2 kcal/g was also included. Channel catfish fingerlings averaging 40 g/fish were stocked into 24, 0.04‐ha ponds at a density of 18,530 fish/ha. Five ponds were used for each dietary treatment except for the all‐plant diet which had four replicates. The fish were fed once daily to apparent satiation for 160 d. No differences were observed in feed consumption, weight gain, survival, carcass and nugget yield, or fillet moisture and protein concentrations among treatments. Fish fed the 28% protein diet had a lower feed conversion ratio (FCR) than fish fed diets containing 24% and 32% protein, but had a FCR similar to fish fed the 36% protein diet. Fillet yield was higher for fish fed the 36% protein diet than fish fed the 24% protein diet. Visceral fat was lower in fish fed the 36% protein diet than fish fed other diets. Fish fed the 32% and 36% protein diets exhibited a lower level of fillet fat than fish fed the 24% protein diet. The 36% protein diet resulted in a lower level of fillet fat than fish fed the 28% protein diet. There was a positive linear regression in fillet yield and fillet moisture concentration and a negative linear regression in visceral fat and fillet fat against dietary protein concentration. No differences in any variables were noted between the 28% protein diets with and without animal protein except that fish fed the 28% protein diet without animal protein had a higher FCR than fish fed the 28% protein diet with animal protein. This observation did not appear to be diet related since FCR of fish fed the 32% protein diet containing animal protein was not different from that of fish fed the 28% all‐plant protein diet. Data from the present study indicate that dietary protein concentrations ranging from 24% to 36% provided for similar feed consumption, growth, feed efficiency, and carcass yield. However, since there is a general increase in fattiness and a decrease in fillet yield as the dietary protein concentration decreases or DEP ratio increases, it is suggested that a minimum of 28% dietary protein with a maximum DEIP ratio of 10 kcal/g protein is optimal for channel catfish growout.     

Fe~(3+)浓度对淡水蛋白核小球藻Chlorella pyrenodiosa生长的影响

在500m L锥形瓶中加入培养基250m L,将氯化铁配制成Fe~(3+)浓度为0μmol/L、3μmol/L、6μmol/L、9μmol/L、12μmol/L、15μmol/L、18μmol/L、24μmol/L、30μmol/L,和36μmol/L 10个梯度,然后在10000Lux光强和恒温28℃下连续培养16d,研究Fe~(3+)浓度对淡水蛋白核小球藻Chlorella pyrenodiosa生长的影响。结果显示:不同浓度的Fe~(3+)先是促进藻类生长,第14d时藻种吸光度最大,是起始浓度的80倍左右,15d后开始抑制藻的生长。这可能是引起藻类爆发、水体富营养化的原因之一。因此治理此类问题时,也要考虑铁离子对藻类生长的影响。     

Dietary Protein Requirements of Juvenile Black Sea Bass,Centropristis striata

A feeding trial was conducted in a recirculating system to determine the dietary protein requirement for juvenile black sea bass. Six isocaloric diets were formulated to contain varying levels of crude protein (CP) ranging from 36 to 56% (36, 40, 44, 48, 52, and 56%) by substituting a mixture of carbohydrates and lipid for fish meal. The feeding experiment was carried out in 18‐75 L aquaria stocked at a density of 15 juveniles (initial average weight 6.7 g) per tank. Fish were fed test diets in triplicate tanks to apparent satiation twice a day for 8 wk. Whole‐body proximate composition was analyzed after the feeding trial. After the feeding trial, weight gain and specific growth rate of fish fed the 44% CP diet were not significantly different from those fed the 48, 52, and 56% CP diets, but were significantly higher (P < 0.05) than those fed the 36 and 40% CP diets. Feed conversion efficiency and protein efficiency ratio were significantly affected by dietary protein level. The dietary requirement of protein for maximum growth of black sea bass juveniles, estimated using broken‐line regression analysis on weight gain, was 45.3% and maximum weight gain occurred at 52.6% based on polynomial regression analysis.